Liquid Crystal Displays (LCDs) are display devices that use light modulating properties of crystal liquids. As the crystal liquids do not emit light directly, the LCDs require a surface light source to evenly illuminate an entire surface of a panel or screen.
Backlighting is a well-known example of a surface light source technology. Back-lighting typically requires, in part, light-emitting diodes (LEDs) as well as a light guide panel on which a reflective layer is formed. In the course of the backlighting, light emitted from LEDs enters into a side edge of the light guide panel. The light emitted into the light guide panel propagates throughout the light guide panel by constantly bouncing from the panel's boundary surfaces by a process of total internal reflection, while diffusing part of the propagating light, thereby allowing the light to be emitted from the front surface of the light guide panel. Thus, the entire area of the light guide panel can be illuminated by the light emitted from the LEDs.